KR20050106275A - Apparatus for uplink data retransmission in code division multiple access communication system and method thereof - Google Patents

Abstract

The present invention relates to a reverse data retransmission method in a reverse communication system using an enhanced reverse dedicated channel. When a user terminal exists in a non-soft handover region, a transmission time period for processing data between a user terminal and a wireless network controller is relatively relatively reduced. By applying a short time, the delay time required for reverse data retransmission is minimized, and when the user terminal is present in the soft handover region, the transmission time interval is relatively long so that recognition information or negative recognition information according to reverse data retransmission is stably To be delivered. In transmitting the cognitive information or negative cognitive information, when the user terminal exists in the non-soft handover area, the cognitive information or negative cognitive information on the reverse data transmitted by the user terminal is determined, and the determined cognitive information or negative cognitive information is determined. Is transmitted to the user terminal, and if it is detected that the user terminal exists in the soft handover area, the recognition information or negative recognition information for the reverse data transmitted by the user terminal is determined, and the determined recognition information or negative recognition information Send to the wireless network controller. Thereafter, the terminal receives final acknowledgment information or negative acknowledgment information about the reverse data from the wireless network controller, and transmits the final acknowledgment information or negative acknowledgment information received from the wireless network controller to the user terminal to maximize the efficiency of reverse data retransmission. .

Description

Method and apparatus for reverse data retransmission in code division multiple access communication system {APPARATUS FOR UPLINK DATA RETRANSMISSION IN CODE DIVISION MULTIPLE ACCESS COMMUNICATION SYSTEM AND METHOD THEREOF}

The present invention relates to a code division multiple access communication system, and more particularly, to a method and apparatus for retransmitting reverse data corresponding to a channel environment of a user terminal.

In general, the asynchronous code division multiple access communication system has evolved into a communication system that enables high-speed packet data transmission as the communication technology is developed. As a communication system capable of high-speed packet data transmission, a high-speed forward packet connection is possible. (HSDPA: High Speed Downlink Packet Access, hereinafter referred to as "HSDPA") A communication system exists. The HSDPA communication system is a forward data channel (HS-DSCH: High Speed-Downlink Shared) for supporting forward high speed packet transmission in a Universal Mobile Telecommunication System (UMTS) communication system developed around Europe. Channel (hereinafter, referred to as "HS-DSCH") is a general term for a data transmission scheme including control channels associated with. In order to support the HSDPA, Adaptive Modulation and Coding (AMC) will be referred to as "AMC" and Hybrid Automatic Retransmission Request (HARQ) will be referred to as "HARQ". And Fast Cell Select (FCS: Fast Cell Select, hereinafter referred to as "FCS") have been proposed. Next, a structure of a wideband code division multiple access (WCDMA) communication system, which is a UMTS communication system, will be described with reference to FIG. 1.

1 is a diagram schematically illustrating a structure of a general WCDMA communication system.

The WCDMA communication system includes a core network (CN) 100, a plurality of radio network subsystems (RNS) (hereinafter, referred to as "RNS"), and a user terminal (UE). : User Equipment, hereinafter referred to as "UE") 130. The RNS 110 and the RNS 120 may be referred to as a Radio Network Controller (RNC: hereinafter referred to as "RNC") and a plurality of base stations (Node B) (Node B or cell in the following description). To use). For example, the RNS 110 includes an RNC 111 and a plurality of Node Bs 113 and 115, and the RNS 120 includes an RNC 112 and a plurality of Node Bs 114 and 116. It consists of. The RNC is classified into Serving RNC (hereinafter referred to as "SRNC"), Drift RNC (hereinafter referred to as "DRNC"), or Controlling RNC (hereinafter referred to as "CRNC") according to its role. The SRNC and the DRNC are classified according to their roles for each UE, and the RNC that manages the information of the UE and is responsible for data transmission with the core network becomes the SRNC of the UE, and the data of the UE is not the SRNC. When the RNC is transmitted and received through the SRNC, the RNC becomes the DRNC of the UE. The CRNC represents an RNC controlling each Node B. For example, when the RNC 111 manages information of the UE 130, the RNC 111 becomes an SRNC, and the UE 130 moves so that the data of the UE 130 is RNC 112. RNC 112 becomes a DRNC when it is transmitted and received through. The RNC 111 controlling the Node B 113 becomes the CRNC of the Node B 113.

Then, with reference to FIG. 1, the HARQ scheme, in particular, a multi-channel SAW HARQ (n-channel SAW HARQ: n-channel Stop And Wait Hybrid Automatic Retransmission Request, hereinafter referred to as "n-channel SAW HARQ") The method will be described.

The n-channel SAW HARQ scheme is described as follows. The n-channel SAW HARQ method represents a method of newly introducing the following two methods in order to increase the efficiency of the conventional Stop and Wait Automatic Retransmission Request (SAW ARQ) method.

The first is a soft combining approach. The soft combining method refers to a method of temporarily storing data in which an error occurs at a receiving side in a soft buffer and combining the data with retransmission of the data to reduce the probability of error occurrence. The soft combining method includes two types of Chase Combining (CC), and Incremental Redundancy (IR). This exists.

In the CC scheme, the transmitting side uses the same format for initial transmission and retransmission. If m symbols are transmitted in one coded block in the first transmission, the same m symbols are transmitted in retransmission. Here, the coding block represents user data transmitted for one transmission time interval (TTI: hereinafter referred to as "TTI"). That is, the same coding rate is applied to the initial transmission and retransmission. The receiving side combines the first transmitted coding block and the retransmitted coding block, performs a cyclic redundancy check (CRC) operation using the combined coded block, and checks whether an error occurs.

On the other hand, in the IR scheme, the transmitting side uses different formats for initial transmission and retransmission. If n bits of user data are generated with m symbols through channel coding, the transmitting side transmits only some of the m symbols in the first transmission and sequentially transmits the remaining portions in retransmission. . In other words, the coding rates of initial transmission and retransmission are different. The receiving side attaches retransmissions to the rear part of the initially transmitted coding block, constructs a coding block having a high coding rate, and then executes error correction. In the IR scheme, the first transmission and each retransmission are distinguished by a version number. The version number of the first transmission is named 1, the version number of the next retransmission is 2, and the version number of the next retransmission is 3, and the receiving side correctly combines the first transmitted coding block and the retransmitted coding block using the version information. can do.

In addition, the IR scheme is classified into a "partial IR" scheme and a "full IR" scheme. "partial IR" means a method of using the same information of some of the formats used for the initial transmission when retransmission, "full IR" means a method that uses a completely different format between the first transmission and the retransmission. When using "full IR", it is possible to obtain the maximum gain due to redundancy information, but in some "full IR" methods, it is impossible to decode the received data only by retransmission. have. Such characteristics are not self-decodable (hereinafter, referred to as "self-decodable"). In the case of channel coding using the turbo encoder, since the systematic bits are not punctured during the initial transmission, the systematic bits are not transmitted again when retransmission is performed using "full IR". In such a case, when the number of bits of retransmission data including only parity bits is not larger than the size of information bits before channel coding, the data cannot be self-decodable. Therefore, when transmitting retransmission data that is not self-decodable, normal reception is possible only by soft combining the initial transmission and retransmission and decoding the received data.

The second method for increasing the efficiency of the n-channel SAW HARQ scheme is the HARQ scheme. In the conventional SAW ARQ scheme, the Node B transmits the next packet only after receiving acknowledgment (hereinafter, referred to as "ACK") information about a previously transmitted packet. However, since the next packet is transmitted only after receiving the ACK information about the previous packet, there may occur a case where the ACK information should be waited even though the Node B can currently transmit the packet. Therefore, the n-channel SAW HARQ scheme can improve the efficiency of use of the radio link by continuously transmitting a plurality of packets even without receiving ACK information about previously transmitted packets. That is, in the n-channel SAW HARQ scheme, n logical channels are established between the UE and the Node B, and the n logical channels are identified by a specific time or explicit channel number, thereby allowing the UE to start at any time. It is possible to know which channel the packet received in belongs to. Thus, the UE may take necessary measures, such as reconfiguring packets or soft combining the packets in the order in which they should be received. Next, the operation of the n-channel SAW HARQ scheme will be described in detail with reference to FIG. 1. First, an n-channel SAW HARQ scheme, particularly a 4-channel SAW HARQ scheme, is performed between the UE 130 and an arbitrary Node B 114, and each of the four channels is assigned a logical identifier from 1 to 4. Suppose you have received it. The UE 130 and the Node B 114 are provided with a mixed automatic retransmission processor (hereinafter, referred to as a "HARQ processor") corresponding to each channel. The Node B 114 assigns a channel identifier of 1 to a coding block to be transmitted first and transmits the same to the UE 130. Here, the channel identifier may be explicitly given or may be implied at a specific time. When an error occurs in a coding block transmitted by assigning the channel identifier of 1, the UE 130 transmits the coding block to a HARQ processor corresponding to the channel identifier 1, that is, HARQ processor 1, and is negative for channel 1. Acknowledgment (hereinafter referred to as "NACK") information is transmitted to the Node B (114). The Node B 114 may then transmit the subsequent coding block on channel 2 regardless of whether ACK information for the coding block of channel 1 has arrived. If an error occurs in a subsequent coding block, the Node B 114 also transmits the subsequent coding block to a corresponding HARQ processor. When the Node B 114 receives NACK information about the coding block of the channel 1 from the UE 130, the Node B 114 retransmits the corresponding coding block to the channel 1, and thus the UE 130 transmits the channel of the retransmitted coding block. The identifier detects the retransmission of the coding block previously transmitted through channel 1 and transmits the retransmission coding block to HARQ processor 1. The HARQ processor 1 receiving the retransmitted coding block soft-combines the first transmitted coding block and the retransmitted coding block already stored. As described above, in the n-channel SAW HARQ scheme, the first transmission and the retransmission can be appropriately corresponded without delaying the user data transmission until the ACK information is received in a one-to-one correspondence between the channel identifier and the HARQ processor.

In order to efficiently use the HARQ scheme as described above, the HSDPA communication system divides the HARQ protocol stack into two layers. That is, in the HSDPA communication system, the soft buffer and error correction function required for soft combining data are placed in the physical layer, and the ACK / NACK is determined. The function of receiving information and determining soft combining is to be located in a media access control (MAC) layer (hereinafter referred to as "MAC"). Meanwhile, the UMTS terrestrial radio access network (UTRAN: hereinafter referred to as "UTRAN") has a Node B and an RNC structure as shown in FIG. The MAC layer, that is, the MAC-hs (MAC-high speed) layer, of the HSDPA communication system is positioned at Node B unlike the general MAC layer. Here, the MAC-hs layer is a layer newly proposed for the HSDPA communication system, and is responsible for an ACK / NACK information processing function for supporting HARQ scheme. The HSDPA communication system performs fast HARQ processing by placing an ACK / NACK information processing function in Node B. Of course, the ACK / NACK information processing function may also be located in the RNC, in which case ACK / NACK information is transmitted to the RNC through the Node B, and the RNC is retransmitted with the ACK / NACK information transmitted through the Node B. It decides whether or not and passes it back to Node B. Then, Node B determines whether or not the actual data is retransmitted based on whether retransmission is transmitted from the RNC. In this case, a delay time for signaling for HARQ processing between the Node B and the RNC occurs. The signaling delay time for HARQ processing between the Node B and the RNC reaches a frame, that is, about 2 ms, thereby acting as a relatively large delay. In order to minimize the delay time for HARQ processing, in the HSDPA communication system, a function of processing ACK / NACK information is located in Node B in HSDPA.

Meanwhile, studies on a reverse communication system for improving reverse communication efficiency together with the HSDPA communication system have been actively conducted. That is, research is being actively conducted on a reverse communication system that enables reverse data transmission using an enhanced uplink dedicated channel (EUDCH), which is a reverse data transmission channel. . In addition, the reverse communication system using the EUDCH may apply the methods used in the HSDPA communication system as described above. That is, the reverse communication system using the EUDCH may use the AMC scheme, the HARQ scheme, etc. used in the HSDPA scheme, and may use a TTI of a relatively short period than the TTI of the HSDPA. The TTI is a unit time period in which one coded block is transmitted as described above, and scheduling for forward channels is performed in the Node B to prevent delay due to scheduling.

As described above, the reverse communication system using the EUDCH transmits data in the reverse direction, and as described in the HSDPA communication system, HARQ scheme support is required for the data transmitted in the reverse direction. However, there is currently no specific proposal for the reverse communication system using the EUDCH, and there is no specific proposal for the HARQ scheme support.

Accordingly, an object of the present invention is to provide a method and apparatus for retransmitting reverse data in a code division multiple access communication system.

Another object of the present invention is to provide a method and apparatus for retransmitting reverse data corresponding to a radio channel environment of a UE in a code division multiple access communication system.

A first method and apparatus of the present invention for achieving the above objects; A method of transmitting data in a code division multiple access communication system,

If the user terminal exists in the non-soft handover region, controlling the transmission of the reverse data in a transmission time interval unit of a first length set in advance;

And if the user terminal is present in the soft handover region, controlling the reverse data to be transmitted in units of a transmission time interval of a second preset length.

A second method and apparatus of the present invention for achieving the above objects; A method for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells,

If the user terminal exists in a softer handover region existing between a plurality of cells belonging to one base station, controlling the reverse data to be transmitted in units of a transmission length of a first length set in advance;

And if the user terminal is present in the soft handover region, controlling the reverse data to be transmitted in units of a transmission time interval of a second preset length.

A third method and apparatus of the present invention for achieving the above objects; An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells,

When the data exists in the softer handover area existing between a plurality of cells belonging to one base station, the reverse data is transmitted in a unit of a transmission length of a first length that is set in advance. A terminal for controlling transmission in units of transmission time intervals of a second length set in advance;

An apparatus comprising a base station serving a terminal and including a plurality of cells.

A fourth method of the present invention for achieving the above objects; An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells,

When present in the soft handover area, the reverse data is transmitted in a unit of transmission length of a second preset length, and in the non-soft handover area, the reverse data is transmitted in a unit of transmission time interval of a preset first length. A terminal for controlling transmission;

A plurality of base stations serving the terminal,

It characterized in that it comprises a base station controller for controlling the base station.

The fifth method of the present invention for achieving the above objects; A method for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells,

If the user terminal exists in the non-soft handover area or one base station exists in the softer handover area including a plurality of cells, the identification information or negative recognition information for the reverse data transmitted by the user terminal is determined, Transmitting the determined cognition information or negative cognition information to the user terminal;

Determining whether the user terminal exists in the soft handover region, determining whether the user terminal has the recognition information or the negative recognition information about the reverse data transmitted by the user terminal, and transmitting the determined recognition information or the negative recognition information to the wireless network controller. and,

Receiving final recognition information or negative recognition information for the reverse data from the wireless network controller after transmitting the determined recognition information or negative recognition information;

And transmitting the final recognition information or the negative recognition information received from the radio network controller to the user terminal.

A sixth method of the present invention for achieving the above objects; An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells,

A terminal for transmitting data to the base station;

If the area where the user terminal exists is located in a non-soft handover area or a softener handover area in which one base station includes a plurality of cells, the identification information or the negative recognition information for the reverse data transmitted by the user terminal is determined. Transmitting the determined cognition information or negative cognition information to the user terminal, and if the user terminal detects that the user terminal exists in the soft handover area, determines the cognition information or the negative recognition information for the reverse data transmitted by the user terminal. Base stations for transmitting the determined recognition information or negative recognition information to a wireless network controller;

And a wireless network controller which receives the recognition information or the negative recognition information transmitted by the base station, generates final recognition information or negative recognition information for the reverse data, and transmits the final recognition information or negative recognition information to the terminal through the base station.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

2 is a diagram schematically illustrating a reverse communication system using an enhanced reverse dedicated channel for performing a function in an embodiment of the present invention.

Before describing FIG. 2, a reverse communication system using the Enhanced Uplink Dedicated Channel (EUDCH) (hereinafter referred to as "EUDCH") as described in the prior art section has a high speed forward packet connection. (HSDPA: High Speed Downlink Packet Access, hereinafter referred to as " HSDPA ") A communication system that is being studied to improve communication efficiency, such as a communication system. That is, reverse data transmission is possible using EUDCH, which is a reverse data transmission channel, and the reverse communication system using the EUDCH can apply the methods used in the HSDPA communication system as described in the related art. have. That is, the reverse communication system using the EUDCH has an adaptive modulation and coding (AMC) scheme and a hybrid automatic retransmission request (HARQ). HARQ ") may be used.

The present invention considers a case where the HARQ scheme is applied to the reverse communication system using the EUDCH among the schemes used in the HSDPA communication system. Considering the case of using the HARQ scheme in a reverse communication system using EUDCH, basically, a user terminal (UE: User Equipment, hereinafter referred to as "UE") is a transmission time interval (TTI: hereinafter "TTI"). Data is transmitted. Then, a UMTS terrestrial radio access network (UTRAN: hereinafter referred to as "UTRAN") determines whether an error occurs in the data received from the UE, and as a result of the determination, the received data When not generated, acknowledgment (hereinafter referred to as "ACK") information, on the contrary, when an error occurs in the received data, negative acknowledgment (hereinafter referred to as "NACK") information is transmitted to the UE. When receiving ACK information from the UTRAN, the UE determines that an error has not occurred in the transmitted data, whereas, when receiving NACK information from the UTRAN, the UE determines that an error has occurred in the transmitted data. . As determined that an error has occurred in the transmitted data, the UE retransmits the transmitted data to the UTRAN, and the UTRAN soft-combines the data retransmitted by the UE and the data in error. This will increase the correction rate.

Meanwhile, the reverse communication system using the HSDPA communication system and the EUDCH has a difference in terms of soft handover support in addition to the difference between the downlink communication system and the uplink communication system. That is, the HSDPA communication system does not support soft handover, whereas the reverse communication system using the EUDCH supports soft handover. In other words, the HSDPA communication system performs service only in one cell serving HSDPA, and supports HARQ scheme only for the corresponding channel performing the HSDPA service, whereas the reverse communication system using the EUDCH When EUDCH service is performed in a plurality of cells at the same time, each of the corresponding channels supports the HARQ scheme. The reason why the reverse communication system using the EUDCH supports soft handover is that high-speed data transmission is important, but to provide stable data transmission regardless of where UEs are located in the cell.

As such, since the reverse communication system using the EUDCH supports soft handover, it is considered impossible to apply the HARQ scheme of the HSDPA communication system as it is. This will be described in detail with reference to FIG. 2 as follows.

Referring to FIG. 2, first, the UE 204 is an overlapping area of the service area of the cell, that is, the base station (hereinafter referred to as "Node B") 202, and the service area of the Node B 203, that is, a soft hand. Assume that it exists in the soft handover region. As the UE 204 is in the soft handover area, the UE 204 will transmit data to both the Node B 202 and the Node B 203. Here, as shown in FIG. 2, data transmitted by the UE 204 in the reverse direction is EUDCH data 212 transmitted to the Node B 202 and EUDCH transmitted to the Node B 203. Data 222. However, as described above, in the HSDPA communication system, the function of determining ACK / NACK information on the forward data is located in the UE, and the function of processing the ACK / NACK information determined by the UE is located in the Node B. Therefore, in the reverse communication system using the EUDCH, it is assumed that a HARQ function including a function of processing ACK / NACK information is located in the Node B like the HSDPA communication system.

Then, the Node B 202 determines whether an error occurs with respect to the EUDCH data 212 received from the UE 204, and if the error does not occur as a result of the determination, ACK information, NACK if an error occurs Information (ACK / NACK 213) is transmitted to the UE 204. In FIG. 2, it is assumed that no error occurs in the EUDCH data 212 received by the Node B 202 from the UE 204. Accordingly, the Node B 202 transmits ACK information to the UE 204. Send it. In addition, the Node B 203 determines whether an error occurs with respect to the EUDCH data 222 received from the UE 204, and if the error does not occur, the ACK information, and if an error occurs, NACK Information (ACK / NACK 223) is transmitted to the UE 204. In FIG. 2, it is assumed that no error occurs in the EUDCH data 222 received by the Node B 203 from the UE 204. Accordingly, the Node B 203 sends NACK information to the UE 204. Send it. As such, when the ACK / NACK information transmitted by the Node B 202 and the Node B 203 is different, a radio network controller (RNC: hereinafter referred to as "RNC") 201 is a macro diver. Since only data without error is received in order to obtain macro diversity, the RNC does not cause any problem even when the ACK / NACK information between Node Bs is different. That is, the Node B 202 transmits the EUDCH data 212 received from the UE 204 to the RNC 201 through a data frame 211 of a frame protocol. The Node B 203 does not transmit the EUDCH data 222 to the RNC 201 because an error occurs in the received EUDCH data 222. As described above, since the RNC 201 receives normal EUDCH data 212 from the Node B 202, even if ACK / NACK information is different between Node Bs, the RNC does not cause any problem.

However, in case of the UE 204, different ACK / NACK information is received for the same data, that is, EUDCH data 212 and EUDCH data 222. That is, the UE 204 receives ACK information from the Node B 202 and NACK information from the Node B 203 with respect to the same EUDCH data 212 and EUDCH data 222. As a result, since the opposite ACK / NACK information is received for the same data, it is impossible to determine whether to retransmit the HARQ scheme.

Of course, unlike the above, when the UE 204 responds only to the ACK information of the ACK / NACK information for each of the EUDCH data 212 and the EUDCH data 222, it is possible to apply the HARQ scheme. However, even if the UE 204 responds only to the ACK information among the ACK / NACK information for each of the EUDCH data 212 and the EUDCH data 222, Node Bs, that is, Node B 202 and Node. The problem arises that the data stored in each of the B 203 soft buffers does not match. In detail, since the UE 204 receives the ACK information from the Node B 202 and the NACK information from the Node B 203, the UE 204 again receives a new EUDCH. It will transmit data. On the other hand, since the Node B 203 has transmitted NACK information on previously received EUDCH data, the EUDCH in which the error has previously been received in the soft buffer provided in the Node B 203 is generated. Data is stored, so the Node B 203 is waiting for retransmission of the EUDCH data in which the error occurred.

However, since the UE 204 transmits new EUDCH data instead of the previously transmitted EUDCH data, new EUDCH data other than the EUDCH data previously transmitted to the Node B 203 that transmitted the NACK information is transmitted. It must be informed, and thus control signaling information indicating that the new EUDCH data is transmitted is required. However, since the UE 204 exists in the soft handover area, the channel environment is very poor due to the characteristics of the soft handover area, and thus it is difficult to reliably transmit the control signaling information. Accordingly, in order for the UE 204 to reliably transmit control signaling information, the control signaling information should be transmitted at a relatively high transmit power, and control signaling having such a high transmit power may interfere with other channels. It can act as an interference component. Therefore, the HARQ scheme of the reverse communication system using the EUDCH must be implemented in a form different from the HARQ scheme of the existing HSDPA communication system.

Accordingly, the present invention newly proposes a HARQ scheme corresponding to a reverse communication system using EUDCH. That is, the present invention considers both HARQ when the UE exists in the soft handover area and when the UE does not exist in the soft handover area, that is, when the UE exists in the non soft handover area. Suggest a way. The present invention proposes the following three schemes for the HARQ scheme corresponding to the reverse communication system using the EUDCH.

The first method applies a relatively short TTI (hereinafter referred to as "TTI _SHORT ") when the UE is in the soft handover area, and when the UE is in the non-soft handover area. It is to apply a relatively long TTI (hereinafter referred to as "TTI _LONG ").

Since the UE in the non-soft handover area is a UE having a relatively good channel environment, it is possible to transmit data at high speed using a relatively large transmission power. Thus, like the HSDPA communication system, the UE transmits data at periodic intervals of TTI _SHORT . Since the UE in the over area is a UE having a relatively poor channel environment, if a relatively large transmission power is used like the UE in the non-soft handover area, the coverage of the UE is reduced, so that data is transmitted periodically in a TTI _LONG cycle. do. In this case, if the HARQ method is performed during the TTI _SHORT , the delay time required for transmitting and receiving data can be minimized, thereby enabling high-speed HARQ operation, thereby increasing communication efficiency of the reverse communication system using the EUDCH. . In addition, if the HARQ method is performed during the TTI _LONG , the data transmission / reception delay time is longer than that of the HARQ method during the TTI _SHORT , but the required HARQ operation time is sufficiently secured to match the ACK / NACK information between the Node Bs. You will have time. The channel environment of the UE is thus good by making it possible to vary the TTI depending on whether the UE is in the soft handover area or the UE is in the non-soft handover area, ie whether the UE's channel environment is poor or good. In this case, high-speed data transmission is possible, and stable data transmission is possible when the channel environment of the UE is poor.

The second scheme is to control the RNC to place a function for determining ACK / NACK information when the UE is in the soft handover area, and ACK when the UE is in the non-soft handover area. The function of determining / NACK information is controlled to be located in Node B.

Prior to describing the second scheme, as described in the prior art, the HARQ protocol stack structure of the HSDPA communication system is divided into two layers. In other words, the HSDPA communication system requires that the soft buffer and error correction functions necessary for soft combining data are located at the physical layer and determine ACK / NACK. The function of determining whether to soft combine by receiving ACK / NACK information is located in a Media Access Control (MAC) layer. Meanwhile, the UMTS terrestrial radio access network (UTRAN: hereinafter referred to as "UTRAN") has a Node B and an RNC structure as shown in FIG. The MAC layer, that is, the MAC-hs (MAC-high speed) layer, of the HSDPA communication system is positioned at Node B unlike the general MAC layer. Here, the MAC-hs layer is a layer newly proposed for the HSDPA communication system, and is responsible for processing ACK / NACK information for supporting HARQ scheme. The HSDPA communication system performs fast HARQ processing by placing an ACK / NACK information processing function in Node B. Of course, the ACK / NACK information processing function may also be located in the RNC, in which case ACK / NACK information is transmitted to the RNC through the Node B, and the RNC is retransmitted with the ACK / NACK information transmitted through the Node B. It decides whether or not and passes it back to Node B. Then, Node B determines whether or not the actual data is retransmitted based on whether retransmission is transmitted from the RNC. In this case, a delay time for signaling for HARQ processing between the Node B and the RNC occurs. The signaling delay time for HARQ processing between the Node B and the RNC reaches one frame, that is, about 10 ms, and thus acts as a relatively large delay. In consideration of the TTI, the delay time for performing the HARQ scheme becomes a relatively large value. Therefore, in the HSDPA communication system, ACK / NACK information is transmitted to the Node B in order to minimize the delay time for performing the HARQ scheme compared to the TTI. A HARQ process function including a function of processing, that is, a function of processing ACK / NACK information is located.

Thus, in the present invention, when the UE exists in the non-soft handover area, both the soft combining / decoding function and the function for determining the ACK / NACK information are placed in the Node B, and when the UE exists in the soft handover area, The soft combining / decoding function in B and the function for determining ACK / NACK information in the RNC are separately located. Of course, when the function of determining the ACK / NACK information is located in the RNC as described in the prior art, the ACK / NACK information is transmitted to the RNC through the Node B, the RNC is transmitted through the Node B ACK / After determining whether to retransmit with NACK information and forwarding to Node B again, the Node B determines whether to retransmit the actual data with the retransmission transmitted from the RNC, signaling for HARQ processing between Node B and RNC There was a problem that a delay time for signing occurred. However, the present invention solves the delay time according to the prior art RNC by determining the ACK / NACK information by applying the TTI _LONG as described in the first scheme, so that the delay time problem is solved.

Next, the second scheme will be described with reference to FIGS. 3 and 4.

3 is a diagram schematically illustrating a HARQ protocol stack structure when a UE exists in a non-soft handover region.

Referring to FIG. 3, since the UE exists in the non-soft handover area, both the soft combining / decoding function and the HARQ 320 function for determining ACK / NACK information exist in the Node B 310. That is, a soft buffer 322 for the soft combining / decoding function, an EUDCH decoder 323, and an ACK / NACK information determiner 321 for a function for determining ACK / NACK information. In addition, all of the ACK / NACK information transmitters 311 transmitting the ACK / NACK information determined by the ACK / NACK information determiner 321 to the UE exist in the Node B 310. When the Node B 310 receives EUDCH data from the UE, the ACK / NACK information determiner 321 determines whether an error has occurred in the EUDCH data received from the UE to determine the ACK / NACK information. Here, the ACK / NACK information determiner 321 determines whether an error has occurred in the EUDCH data received from the UE with a cyclic redundancy check (CRC) test result, and when the CRC test result does not occur, If an error occurs as a result of the CRC test, NACK information is determined. In addition, the ACK / NACK information determiner 321 transfers the EUDCH data received from the UE after the CRC check to the soft buffer 322 to be stored in the soft buffer 322 (data frame, CRC check result) (303). Meanwhile, the ACK / NACK information determiner 321 is a RNC connected to the Node B 310 in which normal EUDCH data is connected to the Node B 310, that is, a data frame 302 of an Iub interface, that is, a frame protocol. To pass through). In addition, the EUDCH decoder 323 decodes EUDCH data received from the UE according to a preset decoding scheme.

In FIG. 3, the HARQ protocol stack structure is described with the UE present in the non-soft handover area. Next, the HARQ protocol stack structure will be described when the UE exists in the soft handover area with reference to FIG.

4 is a diagram schematically illustrating a HARQ protocol stack structure when a UE exists in a soft handover region.

Before describing FIG. 4, since it is assumed that the UE exists in the soft handover area, it is assumed that the UE exists in the soft handover area between the Node B 410 and the Node B 420. It is assumed that the RNCs managing the Node B 410 and the Node B 420 are the same RNC 400. Referring to FIG. 4, since the UE exists in the soft handover area, the soft combining / decoding function and the HARQ function for determining the ACK / NACK information are distributed to the Node Bs 410 and 420 and the RNC 400. Exist. Here, since the HARQ-related functions present in each of the Node Bs 410 and 420 are the same, the Node B 410 will be described as an example. The soft buffer 432, the EUDCH decoder 433, and the ACK / NACK information determiner 431 for determining the ACK / NACK information, and the final ACK / NACK information determiner for the soft combining / decoding function. An ACK / NACK information transmitter 411 for transmitting the ACK / NACK information determined in 402 to the UE exists in the Node B 410, and the final ACK / NACK information determiner 402 exists in the RNC 400. . Here, the ACK / NACK information determiner 431 also exists in the Node B 410, but generates ACK / NACK information for EUDCH data transmitted by the UE, but generated by the ACK / NACK information determiner 431 ACK / NACK information is not transmitted to the UE.

When the Node B 410 receives EUDCH data from the UE, the ACK / NACK information determiner 431 determines whether an error has occurred in the EUDCH data received from the UE to determine the ACK / NACK information. Here, the ACK / NACK information determiner 431 determines whether an error occurs in the EUDCH data received from the UE with a CRC check result, and if the error does not occur as a result of the CRC check, the ACK information, If an error occurs as a result of the CRC test, the NACK information is determined. Also, the ACK / NACK information determiner 431 transfers EUDCH data received from the UE to the soft buffer 432 after the CRC check so as to be stored in the soft buffer 432 (data frame, CRC check result). (403). Meanwhile, when the EUDCH data received from the UE is normal, the ACK / NACK information determiner 431 transfers ACK information and the received EUDCH data to an Iub interface, that is, a data frame of a frame protocol, to the RNC 400. Alternatively, on the contrary, when an error occurs in EUDCH data received from the UE, NACK information is transmitted to the RNC 400 (ACK + data frame, NACK) 403.

Then, the final ACK / NACK information determiner 402 of the RNC 400 uses the ACK / NACK information received from each of the Node B 410 and Node B 420 to ACK the EUDCH data received from the UE. / NACK Generates information. Here, the final ACK / NACK information determiner 402 analyzes the ACK / NACK information received from each of the Node B (410) and Node B 420, and as a result of the analysis the Node B (410) and Node B ( When all the NACK information is received in step 420, the NACK information is determined for the EUDCH data received from the UE. On the contrary, the NACK information is received from any Node B of the Node B 410 and the Node B 420. In this case, ACK information is determined for EUDCH data received from the UE. The final ACK / NACK information determiner 402 determines the final ACK / NACK information determined for the EUDCH data received from the UE by using a control frame of a frame protocol using the Node B 410 and the Node B 420. (404,405). The ACK / NACK information transmitters of the Node B 410 and the Node B 420 then transmit the ACK / NACK information received from the final ACK / NACK information determiner 402 to the UE. In addition, the EUDCH decoder 433 decodes EUDCH data received from the UE according to a preset decoding scheme.

In FIG. 4, the HARQ protocol stack structure is described because the UE exists in the soft handover region. Next, a process of performing the HARQ scheme in a reverse communication system using EUDCH will be described with reference to FIG. 5.

5 is a signal flowchart schematically illustrating a process of performing a HARQ scheme in a reverse communication system using an EUDCH according to an embodiment of the present invention.

Before describing FIG. 5, since the specific channel structure and frame protocol for the reverse communication system using the EUDCH are not defined, parameters related to the HARQ scheme proposed by the present invention are not included. The description will be centered, and the detailed description thereof will be omitted.

Referring to FIG. 5, first, a UE 501 is present in a non-soft handover (non-SHO) region (step 510), and thus the UE 501 may be configured as a first Node B (Node B1) 502. EUDCH data is transmitted in step 511. Here, since the UE 501 is in a non-soft handover area, all HARQ functions, that is, a soft combining / decoding function and a function for determining ACK / NACK information, exist in the first Node B 502. In addition, since the HARQ scheme is performed directly at the Node B terminal, the TTI is also set to the TTI _SHORT . The first Node B 502 performs CRC check on EUDCH data received from the UE 501 and determines ACK / NACK information on EUDCH data received from the UE 501 according to the CRC check result. do. The first Node B 502 transmits the determined ACK / NACK information to the UE 501 (step 512). Meanwhile, when there is no error in EUDCH data received from the UE 501 as a result of the CRC check, that is, when determining ACK information, the first Node B 502 reverses the EUDCH data received from the UE 501. UpLink) is transmitted to the RNC 504 through a data frame (step 513).

The UE 501 may move to the boundary area of the cell to enter the soft handover area after being in the non-soft handover area. Soft handovers can be categorized as softer handovers between cells belonging to Node-B, such as soft handovers that establish multiple radio links between cells belonging to different Node-Bs. Can be. The problem mentioned in the prior art of the present invention is a problem mainly occurring during soft handover between cells belonging to different Node-Bs. Thus, during softer handover, the TTI _SHORT and HARQ operation of the existing non-soft handover is performed. In the case of soft handover, it is more efficient to change to TTI _LONG and HARQ structure as suggested above. To this end, the RNC delivers information indicating whether or not the cell performing the soft handover belongs to a cell belonging to the same Node-B to the UE and the Node-B, and the UE and the Node-B use it to determine whether to change the TTI. Can also be. Alternatively, the RNC determines whether the soft handover of the UE is a soft handover between cells belonging to the same Node-B or a soft handover between cells belonging to another Node-B. For example, a method for informing TTI change in a message indicating an active set update message and in the case of Node-B, a method for informing TTI change information through an Iu signaling message is proposed. In the latter case, the RNC can determine whether to change the TTI according to the type of service of the UE that is currently provided, as well as soft handover, and can instruct the TTI change more flexibly.

In addition, the procedure for receiving soft handover and receiving ACK / NACK information may be performed by the same procedure as for non-soft handover.

The case where soft handover occurs is described below. As shown in FIG. 5, the first node B 502 and the second node B (Node B2) 503 may move to the soft handover (SHO) region (step 520). To this end, the RNC transmits a handover command to the UE through an upper layer signaling message (ACTIVE SET UPDATE) to include the second Node B as an active set. Since an activation time for applying a handover is specified in the upper layer signaling message, a handover operation is performed based on this. Therefore, a UE receiving the upper layer signaling message is deactivated at a corresponding activation time. Upon entering the soft handover area from the soft handover area, the TTI is reset from the TTI _short to the TTI _LONG to transmit the packet data 521.

Here, since the UE 501 exists in the soft handover area, the HARQ function exists separately in the Node Bs 502 and 503 and the RNC 504. That is, the soft combining / decoding function is present in the Node Bs 502 and 503, and the function for determining the ACK / NACK information is present in the RNC 504. Since the HARQ scheme is performed at the RNC, the TTI is also used. Set to TTI _LONG . On the other hand, since the Node Bs 502 and 503 cannot detect that the UE 501 exists in the soft handover area, the RNC 504 goes to the Node Bs 502 and 503. The UE 501 indicates that the soft handover area exists. Here, the RNC 504 informs the Node Bs 502 and 503 that the UE 501 is in a soft handover area using a control frame of a frame protocol. The control frame may include information indicating the entry into the soft handover state and time information indicating the entry time. When the Node Bs 502 and 503 receive the control frame from the RNC 504, the time is transmitted. At the time corresponding to the information, the UE 501 determines that the UE exists in the soft handover area, simultaneously adjusts the TTI to a TTI _LONG , and performs ACK / NACK information performed by each of the Node Bs 502 and 503. The decision function is stopped and operated according to the ACK / NACK information determined by the RNC 504. In addition, since the UE 501 exists in the soft handover area, the UE 501 transmits EUDCH data to both the first Node B 502 and the second Node B 503 (step 521).

The first Node B 502 performs CRC check on EUDCH data received from the UE 501 and determines ACK / NACK information on EUDCH data received from the UE 501 according to the CRC check result. do. Then, if there is no error in the EUDCH data received from the UE 501, the first Node B 502 transmits the received EUDCH data along with ACK information to the RNC 504 through a reverse data frame. In contrast, when there is an error in the EUDCH data received from the UE 501, only NACK information is transmitted to the RNC 504 (step 522). In addition, the second Node B 503 performs a CRC check on the EUDCH data received from the UE 501, and ACK / NACK information on the EUDCH data received from the UE 501 according to the CRC check result. Determine. Then, if there is no error in the EUDCH data received from the UE 501, the second Node B 503 transmits the received EUDCH data along with ACK information to the RNC 504 through a reverse data frame. In contrast, when there is an error in the EUDCH data received from the UE 501, only NACK information is transmitted to the RNC 504 (step 523). Here, when the UE 501 is in a non-soft handover region, the first Node B 502 and the second Node B 503 may receive ACK / NACK information on EUDCH data received from the UE 501. Although directly transmitted to the UE 501, when the UE 501 exists in the soft handover area, ACK / NACK information on EUDCH data received from the UE 501 is directly transmitted to the UE 501. Rather, it is sent to the RNC 504.

The RNC 504 receives ACK / NACK information from each of the first Node B 502 and the second Node B 503, and determines ACK / NACK information according to the received ACK / NACK information to determine the first Node. In step 524, the B 502 and the second Node B 503 are transmitted. Here, when the RNC 504 receives NACK information from both the first Node B 502 and the second Node B 503 as described with reference to FIG. 4, the RNC 504 receives EUDCH data received from the UE 501. When NACK information is determined and ACK is received from any Node B of the first Node B 502 and the second Node B 503, the ACK information is determined for the EUDCH data received from the UE 501. The first Node B 502 determines final ACK / NACK information corresponding to the ACK / NACK information received from the RNC 504 and transmits the final ACK / NACK information to the UE 501 (step 525). Similarly, the second Node B 503 also determines final ACK / NACK information corresponding to the ACK / NACK information received from the RNC 504 and transmits the final ACK / NACK information to the UE 501 (step 526). As described above, when the UE 501 is in a soft handover area, the RNC 504 is configured to separate Node Bs by separating HARQ-related functions from the Node Bs 502 and 503 and the RNC 504. Macro diversity can be obtained since the EUDCH data without error is received from 502 and 503, and the UE 501 can receive the same ACK / NACK from Node Bs 502 and 503. Since the information is received, the normal HARQ scheme can be performed.

As described above, the UE receives ACK / NACK information on the EUDCH data transmitted from the UE, and when the UE receives the ACK information, the UE does not take a separate operation, and when the NACK information is received, the transmission is performed. Retransmission is performed for one EUDCH data.

Next, a third scheme required for the HARQ scheme corresponding to the reverse communication system using the EUDCH of the present invention will be described as follows.

The third method is a soft combining method in which the UE exists in a non-soft handover region. Chase Combining (CC) and an increase in overlap (IR: Incremental Redundancy (hereinafter referred to as " IR ") scheme, and when the UE is in the soft handover region, the CC scheme and IR scheme with a limited version number are used. . Here, the "limited version number" refers to a version number that is self-decodable (hereinafter, referred to as "self-decodable") among the version numbers. The self-decodable means that when data is received as described in the prior art, decoding to information data without error using only the received symbol data is possible. In actual implementation, channel coding is performed. In this case, the coding rate and the IR version number determine the self-decodable.

On the other hand, when the UE exists in the soft handover area, since the UE exists in the cell boundary area of each of the Node Bs, the channel environment is likely to be poor. Thus, when the UE exists in the soft handover area, the Node Bs may receive data in error or may not receive data transmitted by the UE. If the Node Bs do not receive the data transmitted by the UE, if the UE retransmits the data using a version number that is not self-decodable, the Node B, which has not received the data itself at the UE, may receive soft data about the data. Since there is no data buffered for combining, the error is likely to occur again. In order to prevent the recurrence of such an error, in the present invention, when the UE exists in the soft handover area, only the self-decodable version number is used for the version number of the retransmitted data. By retransmitting data using only the self-decodable version number, Node Bs can receive data normally even if there is no data to soft combine.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention relates to HARB-related functions according to the radio channel environment of the UE in the reverse communication system using the EUDCH, that is, whether the UE exists in the soft handover region or the non-soft handover region. Distributed to the RNC has the advantage of enabling stable reverse data retransmission. In addition, when the UE exists in the soft handover region, the time required to perform the ACK / NACK information determination by adjusting the TTI for a time delay that may occur as the RNC performs ACK / NACK information determination on the reverse data. This has the advantage of allowing sufficient reverse data retransmission by ensuring enough.

1 schematically illustrates the structure of a typical WCDMA communication system.

2 is a diagram schematically illustrating a reverse communication system using EUDCH for performing a function in an embodiment of the present invention.

3 schematically illustrates a HARQ protocol stack structure when a UE exists in a non-soft handover region.

4 is a diagram schematically illustrating a HARQ protocol stack structure when a UE exists in a soft handover region;

5 is a signal flowchart schematically illustrating a process of performing a HARQ scheme in a reverse communication system using an EUDCH according to an embodiment of the present invention.

Claims (14)

A method of transmitting data in a code division multiple access communication system, If the user terminal exists in the non-soft handover region, controlling the transmission of the reverse data in a transmission time interval unit of a first length set in advance; And if the user terminal is present in the soft handover area, controlling the reverse data to be transmitted in units of a second transmission length of a preset length. The method of claim 1, The method of claim 2, wherein the transmission time period unit of the second length is set larger than the transmission time period unit of the first length. The method of claim 1, The transmission time interval unit of the second length is 10ms, and the transmission time interval unit of the first length is characterized in that 2ms. The method of claim 1, Wherein the TTI change is applied to an enhanced reverse packet data service. A method for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells, If the user terminal exists in a softer handover region existing between a plurality of cells belonging to one base station, controlling the reverse data to be transmitted in units of a transmission length of a first length set in advance; And if the user terminal is present in the soft handover area, controlling the reverse data to be transmitted in units of a second transmission length of a preset length. The method of claim 5, The method of claim 2, wherein the transmission time period unit of the second length is set larger than the transmission time period unit of the first length. The method of claim 5, The transmission time interval unit of the second length is 10ms, and the transmission time interval unit of the first length is characterized in that 2ms. The method of claim 5, Wherein the TTI change is applied to an enhanced reverse packet data service. An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells, When the data exists in the softer handover area existing between a plurality of cells belonging to one base station, the reverse data is transmitted in a unit of a transmission length of a first length that is set in advance. A terminal for controlling transmission in units of transmission time intervals of a second length set in advance; And a base station serving the terminal and including a plurality of cells. The method of claim 9, The apparatus of claim 2, wherein the transmission time period unit of the second length is set larger than the transmission time period unit of the first length. An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells, When present in the soft handover area, the reverse data is transmitted in a unit of transmission length of a second preset length, and in the non-soft handover area, the reverse data is transmitted in a unit of transmission time interval of a preset first length. A terminal for controlling transmission; A plurality of base stations serving the terminal, And a base station controller for controlling the base station. The method of claim 11, The apparatus of claim 2, wherein the transmission time period unit of the second length is set larger than the transmission time period unit of the first length. An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells, If the user terminal exists in the non-soft handover area or one base station exists in the softer handover area including a plurality of cells, the identification information or negative recognition information for the reverse data transmitted by the user terminal is determined, and Transmitting the determined cognition information or negative cognition information to the user terminal; Determining whether the user terminal exists in the soft handover region, determining whether the user terminal has the recognition information or the negative recognition information about the reverse data transmitted by the user terminal, and transmitting the determined recognition information or the negative recognition information to the wireless network controller. and, Receiving final recognition information or negative recognition information for the reverse data from the wireless network controller after transmitting the determined recognition information or negative recognition information; And transmitting final recognition information or negative recognition information received from the wireless network controller to the user terminal. An apparatus for transmitting data in a code division multiple access communication system in which one base station includes a plurality of cells, A terminal for transmitting data to the base station; If the area where the user terminal exists is located in a non-soft handover area or a softener handover area in which one base station includes a plurality of cells, the identification information or the negative recognition information for the reverse data transmitted by the user terminal is determined. Transmitting the determined cognition information or negative cognition information to the user terminal, and if the user terminal detects that the user terminal exists in the soft handover area, determines the cognition information or the negative recognition information for the reverse data transmitted by the user terminal. Receiving base station transmitting the determined cognitive information or negative cognitive information to a wireless network controller, receiving cognitive information or negative cognitive information transmitted by the base station, and generating final cognitive information or negative cognitive information on the reverse data; Through the base station The device characterized by consisting of a radio network controller for transmitting to the end.